1. Field of the Invention
This invention relates to a pipe clamp device, primarily for use with socket and spigot pipe joints which the socket may be formed in one of two pipes to be joined or in a separate socket member used to interconnect a pair of pipes of uniform diameter, or to receive a single pipe, the device being operable to compress an external sealing ring, often for the purpose of repairing a leaking joint.
2. Description of the Prior Art
Underground pipes for the transport of liquids and gases are usually in the form of a succession of pipe sections joined together longitudinally by spigot and socket joints which normally incorporate a packing material between internal opposing surfaces of the joint for sealing purposes. While such joints can remain leak-free for a number of years, the effects of ground movement and vibration and/or degradation of the packing can result in eventual leakage of the joint, with possibly disastrous consequences, particularly in the case of gas pipes.
It has become common practice to repair leaking joints of the aforesaid kind by the application of a resilient sealing gasket against adjacent external surfaces of the joint, such ring being compressed generally axially against said surfaces by a clamping device to seal off the leak. An example of such a clamping device used with a spigot and socket joint formed by a pair of pipe end portions is shown in U.S. Pat. No. 2,822,195 and consists of an anchor ring which engages behind a shoulder of the socket and a clamp ring for engagement with a gasket placed around the spigot-bearing pipe and against the free end of the socket. Clamping bolts extending between the two rings may be tightened to draw the rings towards one another and produce a generally axially directed sealing force on the gasket. It has been found, in practice, however that this type of arrangement can often deform the gasket in such a manner that its sealing action is not wholly effective or becomes insufficiently effective as a result of subsequent seal relaxation and/or deformation of the pipe joint parts.